1. Field of the Invention
The present invention relates to a fuel cell. More specifically, the present invention relates to a fuel cell that uses alcohol as fuel and a method for manufacturing such a fuel cell.
2. Description of the Related Art
Japanese Patent Application Publication No. 2002-270209 (JP-A-2002-270209), for example, describes a polymer electrolyte fuel cell having an anode configured to be advantageous when a fuel other than hydrogen is used. Specifically, a layer containing a biochemical catalyst is formed over the surface of the anode of the fuel cell. The biochemical catalyst layer catalyzes the degradation of the raw materials of the fuel to generate hydrogen.
That is, if methanol is used as the fuel, for example, the methanol is degraded as it passes through the biochemical catalyst layer. At this time, hydrogen is produced in the biochemical catalyst layer. The hydrogen is supplied to the anode at the inner side (at the side of an electrolyte film) to generate protons and electrons. Thus, according to the above related art, pure hydrogen is supplied to the anode even when an alcohol, such as methanol, is used as the fuel, and therefore it is possible to reduce poisoning of the anode by carbon compounds contained in the fuel.
If the fuel cell uses a fuel other than pure hydrogen, such as alcohol, for example, the proportion of hydrogen contained in the fuel is low. Therefore, in order to improve the power generation performance of the fuel cell using a fuel other than pure hydrogen, it is important to efficiently degrade the fuel and generate hydrogen. For this purpose, in the related art described in JP-A-2002-270209, Japanese Patent Application Publication No. 2004-71559 (JP-A-2004-71559), and Published Japanese Translation of PCT Application No. 2006-508519 (JP-A-2006-508519), poisoning of the anode is reduced by supplying pure hydrogen generated in the biochemical catalyst layer to the anode at the inner side. In the described fuel cells, however, the efficiency and rate of the reaction to generate hydrogen in the biochemical catalyst layer are not taken into account. In order to improve the power generation performance of the fuel cell by improving the utilization efficiency of fuel, it has been expected to develop an electrode that can generate hydrogen from the fuel at a higher efficiency.